A semiconductor device such as an integrated circuit (IC) used in an electronic apparatus can be damaged or the characteristics thereof can be degraded by electrostatic discharge (ESD). Especially, recent semiconductor devices require a high-speed operation, and are thus brittle to ESD. When the semiconductor device is damaged by ESD, the electronic apparatus undergoes a serious obstacle such as a malfunction or failure. Therefore, recently, the importance of measures against ESD becomes high in various electronic apparatuses, and varistors that include a voltage nonlinear resistor having a voltage nonlinearity as an anti-ESD component are widespread.
A varistor used for the measures against ESD must have an excellent characteristic of absorbing the ESD, and have a high ESD resistance so that the varistor itself is not damaged by the ESD. In a state where there is no intruding ESD, the varistor serves simply as capacitance. Therefore, the varistor must have an appropriate capacitance value within the range where an operation of a circuit is not adversely affected.
Such voltage nonlinear resistors used for the measures against ESD are generally classified into two types, Pr base (for example, Patent Literature 1) and Bi base (for example, Patent Literature 2), depending on a varistor characteristic exhibiting additive. A Pr-based multilayer varistor is appropriate for lowering the varistor voltage, and a Bi-based multilayer varistor is appropriate for decreasing the capacitance. The varistor voltage and capacitance can be adjusted by appropriately selecting one of two material bases and appropriately setting the thickness of the varistor layer between electrodes and the overlap area of the electrodes.